Autism

Introduction

Autism

Autism, also known as autism spectrum disorder (ASD), is a disorder that causes impairment in social interaction, as well as the presence of repetitive, restricted behaviors and interests. It is usually first diagnosed in early childhood.

The term spectrum refers to the wide range of symptoms, skills, and levels of impairment that those with ASD can have. Some are mildly impaired by their symptoms, while others are severely disabled. According to the Centers for Disease Control and Prevention, ASD affects roughly 1 in 68 children.

What are some of the symptoms of autism?

Although people with autism have a range of symptoms that vary in severity, they all have difficulties communicating and interacting with others, and show restricted and repetitive patterns of behavior and interests. Most symptoms are noticeable by the time a child is 2-3 years old, but many children are not diagnosed until later. Early intensive behavioral intervention can improve communication, learning, and social skills in children with autism.

Autism affects people for their entire lives, and often comes with other conditions, such as epilepsy, sleep disturbances, and gastrointestinal problems. Currently, no drugs have proven effective for treating core autism symptoms.

How is autism diagnosed?

The new DSM-5 criteria encourage diagnosis prior to school age. Children with ASD must show symptoms from early childhood, although the symptoms may not be recognized until later. Sometimes symptoms are not evident until children are old enough to be in social situations that challenge their capacity to respond.

What causes autism?

Although recent studies indicate that the rate of ASD is rising, the causes of these disorders are not well-understood. Over time, scientists have found that rare gene changes, or mutations, as well as small common genetic variations, are associated with ASD, thus implying a genetic component. However, a growing area of research indicates that ASD may be caused by an interaction of genetic and environmental factors.

For example, one hypothesis states that ASD may be triggered by a mother’s exposure to environmental agents while pregnant. These exposures, in turn, could cause or contribute to the child’s development of ASD.

A 2014 study pointed to a likely gene-environment interaction. Children whose genetic makeup causes them to be more susceptible to the health effects of high levels of air pollution showed the highest risk for autism.

Prenatal conditions

Researchers funded by NIEHS discovered that problems with the immune system, as well as maternal conditions during pregnancy, are linked with higher autism risk.

No link between autism and vaccines containing thimerosal, a mercury-based compound, has been found.

This content is available to use on your website.
Please visit NIEHS Syndication to get started.

What NIEHS is Doing on Autism

NIEHS has steadily increased funding of autism research over the last decade, and this investment is producing important new discoveries that may help prevent autism. For example, NIEHS-funded researchers have shown that taking folic acid and avoiding infections during pregnancy can help lower autism risk. Researchers have also shown that problems with the immune system are involved in autism, and that early-life exposure to high levels of air pollution may increase risk, especially for children whose genetic makeup causes them to be more susceptible.

The NIEHS Autism Research Program has attracted talented scientists from toxicology, epidemiology, and other areas. These researchers are using new ways to measure prenatal exposures, screen for contaminants that affect brain development, and understand how environmental factors interact with genes to lead to autism.

CHARGE is an ongoing exploration of more than 1,800 children, to clarify the roles of genetics and environmental exposures in ASD development. Recently published findings from CHARGE showed that pregnant women who lived near farms using certain pesticides were more likely to have children with ASD or developmental delay than pregnant women who lived more than 1.5 kilometers from farms using these pesticides.

In a separate study led by NIEHS-funded scientists from the University of Southern California, researchers found that children possessing a specific genetic risk factor appear more likely to develop ASD when exposed to high levels of air pollution while in the womb. This finding helps explain why some previous studies that focused exclusively on genetic variation and ASD development have proven inconclusive.

NIEHS involvement with the IACC

NIEHS is one of the federal members of the Interagency Autism Coordinating Committee (IACC). Dr. Linda Birnbaum, NIEHS director, is the primary NIEHS representative to the IACC and Dr. Cindy Lawler, chief of the NIEHS Genes, Environment, and Health branch, is the alternate.

NIEHS works in partnership with other members of the IACC to summarize advances in autism research and participate in strategic planning for research needs. The IACC hears directly from members of the public regarding their concerns about autism and recommendations for research needs.